This invention relates to motor controllers, and, more particularly, to thermally efficient motor controller assemblies.
U.S. Pat. No. 5,341,080 entitled Apparatus and Three Phase Induction Motor Starting and Stopping Control Method, describes starters and contactors used to efficiently start and stop industrial rated electric motors. A more recent example of a motor controller unit is found in U.S. Pat. No. 5,760,556 entitled Motor Controller and Protector Unit. In such motor controllers and electrical contractors, solid state switches, such as silicon controlled rectifiers (SCR), for example, are often employed to controllably switch the motor current to provide smooth motor starting and stopping function. Since the SCR's become heated upon current transfer therethrough, heat sinks in the form of large metal blocks of copper, aluminum and their alloys are required to protect the SCR's from overheating. The SCR's are usually spaced apart from the other motor controller components to facilitate cooling. Electrical connection between the SCR's and the other motor controller components is made by means of electrically-insulated thick metal cables, one for each phase of the associated electrical distribution system.
U.S. patent application Ser. No. 08/904,293 entitled Compact Electrical Equipment Enclosure, describes an equipment enclosure that is open at the rear thereof to provide an air flow, so called "chimney effect." The SCR's connecting with the motor controller are arranged apart from the other motor controller electric components within the air flow path to promote thermal cooling effects. The placement of the SCR's apart from the other electrical components increases the size of the equipment enclosure to some extent. This size limitation is critical when other devices such as circuit breakers and contactors are interconnected as described in U.S. Pat. No. 5,657,193 entitled Electronic Control Module for Motor Controller Units.